A suspected case of measles has cropped up at a second Ann Arbor elementary school.

That makes four potential cases of the highly contagious disease at two elementary schools in the city over the past week.

A student at Angell Elementary School has what's believed to be the measles, school and county public health officials said Monday.

Last week, one confirmed case of the measles and two probable cases occurred at Burns Park Elementary School, said Stan Reedy, medical director of the Washtenaw County Public Health Department. All three of the students had been vaccinated, Reedy said.

Officials said there is a direct link between the Angell student and the confirmed case at Burns Park. The contact came through a sporting event, said Gray Reynolds, public information officer for the county Health Department.

During roughly the first 10 days following exposure, a child has dramatic viral and immunologic activity taking place inside her body, with virtually no outward sign of illness.

Next, typically, comes the prodromal period in which she has symptoms of a cold (tiredness, runny nose, cough, and perhaps red eyes) but with a high fever (~39.5 C or 103 F). These symptoms gradually increase over about 4 days.

During these 4 days, she has white spots in her mouth. These are called Koplik spots and are the hallmark of measles. They usually start on the inside of the cheek opposite the lower molars, then spread within 12 hours to cover most of the inside of the cheeks and lower lip. Many things can cause white spots in the mouth; Koplik spots always appear on a bright red, granular background.

The typical measles rash begins about 14 days after exposure (or 4 days after appearing ill). The fever is still at its height when the rash appears (in contrast to an infection called Roseola).